Kroemer joins RCA Laboratories at Princeton where he tries - unsuccessfully - to build some HBTs with a Ge/Si alloy emitter on a Ge base. He writes also two theoretical papers. One of these, in the RCA Review, clearly expresses the concept of quasielectric fields, a fundamental design principle for all heterostructures. In 1957, Kroemer calculates that a heterostructure transistor would be superior to a conventional transistor, especially for certain high-frequency uses and other applications.
Herbert Kroemer returns to Germany to head Phillips Semiconductor Group, working on gallium arsenide technology.
Herbert Kroemer is employed at the Central Telecommunications Laboratory (FTZ) as theoretical consultant.
Herbert Kroemer is admitted at the University of Göttingen. He writes a theoretical Diploma Thesis under Professor Fritz Sauter on the nature of surface states in one-dimensional potentials looking also at the interface between two different periodic potentials.
In a 1954 publication Kroemer expresses the first ideas for the heterostructure bipolar transistor, or HBT. Heterostructure devices make fibre-optic communications possible and are used today in several everyday products, including computers. Kroemer proposes both a transistor with a graded gap throughout the base, and the simpler form of just a wide-gap emitter.
Herbert Kroemer enters University of Jena where he is enchanted by Friedrich Hund. After the political suppression in East Germany becomes severe in 1948, Kroemer decides to go to West Germany.
Herbert Kroemer receives one quarter of the Nobel Prize in Physics along with with Zhores Alferov "for developing semiconductor heterostructures used in high-speed- and opto-electronics". The other half of the Nobel Prize goes to Jack Kilby.
During the Soviet blockade of Berlin in 1948, Herbert Kroemer joins for the summer the AEG research laboratories where Dr. Poganski shows him that the selenium rectifier is not a Schottky barrier, but a p-n junction between p-type selenium and n-type CdSe.
Herbert Kroemer joins the University of California at Santa Barbara, where he turns to experimental work. Here he researches on superconductor-semiconductor hybrid structures involving InAs-AlSb quantum walls contacted by superconducting niobium electrodes, and (ii) current transport in semiconductor superlattices under influence of high electric fields perpendicular to the superlattice planes, with emphasis on theoretical understanding of the resulting Bloch oscillations.
Herbert Kroemer is born in Weimar. His parents pretend from him top performance at school but at the same time let him free to follow his inclination and to choose without pressures his own academic direction.
Herbert Kroemer earns his Ph.D. at University of Göttingen with a dissertation on hot-electron effects in the collector space-charge layer of the newly discovered transistor.
Herbert Kroemer joins Varian Associates in Palo Alto. In 1963 he proposes the concept of the double-heterostructure laser but he cannot develop the idea because of funds lacking. He begins then working on the Gunn effect.
Herbert Kroemer becomes Professor of Electrical Engineering at the University of Colorado.